I was just wondering if it was allowed to sell drawings of users to the user for use? So lets say im person A. I request a drawing on my head-shot. Person B comes along and says I can do it for you. Are you allowed to charge the user a commission (In sP) for drawing them, because I can do some beast drawings (With pencil blah blah).

Is this allowed, and would I be able to say "Taking art request, Prices are as follows"?

Yes you can. If you looks down a few boards you'll see the Art Market.